did you install 9ias?
have any problems? 
please post the exact message here.
general prcedure is ( depending on the need).
1. first you need to install infrastructure.
2. then install the middle tier ( you can choose the options of portal/discoverer/report/forms etc).
it is recomended to have the infrastructure and 
middletier in seperate machines THOUGH it is not a must. Both will work good in the same host too.
3. then install your J2EE stuff.

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1. after every installation and autoconfiguration some messages pop out.
they contain the url witha specific port  for httpserver and enterprise manager website. NOTE THEM Carefullly.
2. once you are done with the installation ( wiz, a customer database IASDB is automatically created for demos), goto the EM website make sure the the concerned services are available.
3. got the demopage , check the demos.
   for discoverer plus, it will automatically install
   required compoents for JInitiator.
4. GO THROUGH THE ORACLE APPLICATION SERVER documentation. everything is clearly explained.
5. first start playing around with dcmctl , emctl , oid
etc. 
first you need start the database and listener, then oracle HTTP , oc4j etc.then you can port your applications/reports.